Plate heat exchanger

ABSTRACT

A plate heat exchanger of the type comprising a shell housing circular discs arranged in succession separated by sealing rings. The discs are provided with two sets of openings for passage therethrough of a first medium and a second medium, respectively. The first set of openings for the first medium is positioned close to the outer periphery of the discs, i.e., radially outside of the separating rings, while the second set of openings for the second medium is positioned radially inside the separating rings. According to one embodiment of the invention the second set of openings are notches formed at the edge portion of a central hole passing through the discs and through which hole flows one of said media. According to another embodiment of the invention the discs are mounted on an axial tube the inner end of which extends inside the shell and is formed with slots but is otherwise closed, this tube end being also provided with a sleeve serving to guide medium flowing through the tube and passing through the slots, in through the notches at the central hole of the discs.

, tinned States Patent 1 91 Ostbo PLATE HEAT EXCHANGER [76] Inventor: Karl Robert Ambjom Ostbo, Storgatan 2, S-5 10 Tranerno, Sweden [22] Filed: Feb. 18, 1971 i 21 Appl.No.: 116,423

, 301 Foreign Application Priority Data FOREIGN PATENTS OR APPLICATIONS 851,821 10/1939 France 800,248 10/1950 Germany 18,516 1888 l 65/ 1 79 Great Britain.- 165/179 [451 May 29,1978

Primary Examiner-Charles J. Myhre Assistant Examiner-Theophil W. Streule, Jr. Attorney-Newton, Hopkins & Ormsby [5 7] ABSTRACT A plate heat exchanger of the type comprising a shell housing circular discs arranged in succession separated by sealing rings. The discs are provided with two sets of openings for passage therethrough of a first medium and a second medium, respectively. The first set of openings for the first medium is positioned close to the outer periphery of the discs, i.e., radially outside of the separating rings, while the second set of openings for the second medium is positioned radially inside the separating rings. According to one embodiment of the invention the second set of openings are notches formed at the edge portion of a central hole passing through the discs and through which hole flows one of said media. According to another embodiment of the invention the discs are mounted on an axial tube the inner end of which extends inside the shell and is formed with slots but is otherwise closed, this tube end being also provided with asleeve serving to guide medium flowing through the tube and passing through the slots, in through the notches at the central hole of the discs.

3 Claims, 17 Drawing Figures PAINTED- 3,735,810

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BACKGROUND OF THE INVENTION The present invention relates to a universal-type plate heat exchanger.

Prior-art plate heat exchangers are usually quite bulky and have a complicated structure, and for this reason they are expensive to manufacture. In addition, the plates are generally interconnected by means of bolts passing through them and usually these bolts have to be reckoned with when choosing the path of flow of the media passing through the exchanger. As a rule, a heat exchanger of plate-type is designed with a particular function in mind, i.e. for particular through-flow media, the particular amount of heat transfer, etc. Furthermore, dismantling of a plate heat exchanger for repairs,.cleaning, inspection and like purposes has hitherto been complicated.

BRIEF SUMMARY OF THE INVENTION of and radially inside of sealing rings arranged in the gap formed between adjacent metal plates, for separating the two media. The invention is characterized by the fact that the radially inner openings are notches formed at the edge portion of a center hole in the metal plates, adapted to the flowed through by one of the media. Because the radially inner openings made in the metal plates are designed as edge notches formed at the periphery of the central plate hole in which the first medium flows, heat transfer between one medium and the other one is extremely good, which imparts to the efficiency of the heat exchanger.

One embodiment of the invention is characterized by an axial tube presenting at its one end a flange for attachment to a flange formed at one end of the shell, and presenting at its opposite end, which end is positioned in the shell interior, through-passage openings formed in the tube jacket, said tube being here otherwise closed, and by a sleeve mounted on the latter tube end, said sleeve being adapted to guide medium introduced into the tube and passed out through said throughpassage openings, in through said edge notches formed at the center hole in the metal plates. This embodiment of the heat exchanger provides the considerable advantage of making possible separation of the two media in the heat exchanger in a simple way without the use of complicated seals.

BRIEF DESCRIPTION OF THE DRAWINGS Further characteristics and advantages of the invention will become apparent upon reading of the following detailed description with reference to the accompa- FIG. 3 is a perspective view of two plates and their intermediate sealing rings on a portion of the longitudinal tube;

FIG. 4 shows on an enlarged scale an end view of the heat exchanger plate assembly;

FIG. 5 is a cross-sectional view of a portion of the plate assembly;

FIGS. 6, 7, and 8 are cross-sectional views through three different sealing rings;

FIG. 9 is a vertical longitudinal section through the heat exchanger in accordance with another embodiment of the invention;

FIG. III illustrates on an enlarged scale a vertical longitudinal section through the plate assembly of the heat exchanger in accordance with the second embodiment;

FIG. 11 is a longitudinal section through a heat exchanger in accordance with a somewhat simplified embodiment;

FIG. 12 shows on an enlarged scale a longitudinal section through the plate assembly of the heat exchanger;

FIG. ]13 is an end view of one half of one of the metal plates of the heat exchanger;

FIG. 14 is a longitudinal section through a heat exchanger provided not only with inner and outer through-passage channels for one of the media but in addition with an intermediate through-passage channel for the other medium;

FIG. 15 illustrates a vertical longitudinal section through a similar heat exchanger installed as an economizer in the flue gas outlet of a heater;

FIG. 16 illustrates on an enlarged scale a longitudinal section through one end of a plate assembly of the heat exchanger illustrated in FIG. 14, and

FIG. 17 is a cross-sectional view through this plate assembly along line XVII--XVII in FIG. 16.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT The external structure of the plate heat exchanger in accordance with the invention comprises an essentially cylindrical jacket or shell 1 with an inlet 2 and an outlet 3 for the outer through-flow medium and an inlet 41 and an outlet 5 for the inner through-flow medium. The inlet 4 for the inner through-flow medium is arranged at the outer end of an axial tube 6 the inner end 7 of which extends into the far end of the shell 1 where the outlet 3 for the outer through-flow medium is positioned. The outlet 5 for the innerv through-flow medium is arranged adjacent the outer end of a pipe 8 which together with tube 6 forms a passage 9 for the inner through-flow medium. The pipe 8 is provided with a flange 10 fitting a similar flange 111 formed at one end of the shell. A washer 12 is arranged between flanges 10 and 11, and a number of bolts 13 are arranged to tighten said washer.

A number of circular metal plates 14 are mounted on the tube 6, each one of said plates presenting a plurality of radially outer openings 15 and a plurality of radially inner openings 16. Between adjacent metal plates M a sealing ring 17 of rubber, copper, asbestos or the like is arranged. The material of the sealing rings 17 is chosen in accordance with the nature of the throughflow media, the working temperature, and like factors of interest in each particular case. In addition to being medium separating means, the sealing rings 17 also serve as distance means between the metal plates M.

The radially outer openings preferably are formed through punching radial tongues 18 in the plates which tongues are thereafter bent at an angle so as to project from one side of the plate 14. The radially inner openings 16 are notches formed at the edge 19 of a center hole 20 formed in each plate 14 and through which hole 20 the tube 6 extends.

The plates 14 are mounted on the tube 6 and so positioned that the openings 15 in adjacent plates become angularly displaced or staggered relatively each other, as appears from FIGS. 4 and 5 whereby the outer through-passage medium is forced to be repeatedly deflected when passing through the heat exchanger. The

' same staggered relationship applies to the positioning of edge notches 16.

The inner end 7 of the tube 6 is provided with longitudinally extending slots 21 formed in the tube jacket. This tube end 7 is otherwise closed by means of an externally threaded pin 22 which is provided with a nut 23. Asleeve 24 is threaded onto tube end 7 and this sleeve is designed so as to form an annular gap 25 outside the slots 21. In the outer end of the sleeve 24 is inserted a ring-shaped seal 26 with an abutment ring 27 and a number of disc springs 28 positioned between said ring and the nut 23.

As appears from FIG. 1 the entire plate assembly is urged against the inner end of the pipe 8 when the nut is being tightened, the axial pressure required to establish good sealing effect between plates 14 and rings 17 being obtained through the spring force of the disc springs 28, and this irrespective of any variations in the length of tube 6 that might occur as a result of variations in temperature.

The arrows indicated in FIG. 1 illustrate the flow direction of the two media. Thus, the outer medium is introduced through inlet 2, flows through openings 15 formed in the plate 14 and further out through the outlet 3 in the far end of the shell 1. The inner medium is introduced through inlet 4, flows through the tube 6 and further through the slots 21 and the annular gap 25 and through the notches 16 and into passage 9 and out through outlet 5. It is evident that the heat-transfer through plates 14 becomes very efficient, above all because of the short distance through the material in the plates 14 from the openings 15 to openings 16 or vice versa.

As illustrated in FIGS. 6, 7 and 8, the sealing rings 17, 17', 17" may be given different shapes. Two O-rings 29 are used for sealing ring 17".

The embodiment illustrated in FIG. 9 is externally constructed in the same way as the embodiment shown in FIG. 1. However, the pin 22, nut 23, sleeve 24 and spring means 28 are eliminated in the embodiment in accordance with FIG. 9. Instead the outer end 7' of the tube 6' in this embodiment is completely open. The metal plates 14' are attached to their sealing rings 17 through projection welding such that the entire plate assembly forms one single, rigid unit. To the metal plate positioned at the inner end of tube 6' is welded a sleeve 31 with an end portion 30 such that an annular channel 25' is formed between tube end 7 and the jacket of the sleeve 31.

Also in accordance with this embodiment, the plates 14 are turned relatively each other before the welding such that both the radially outer through-passage openings l5 and the radially inner openings 16 will be angularly displaced or staggered relatively each other, thus forcing the media to flow through the heat exchanger in a zig-zag pattern or in constantly changing directions.

The metal plates 14 are preferably made from a non- .corrosive material having high coefficient of thermal conductivity, such as for instance stainless steel, aluminium-brass, niccolite etc.

The plate heat exchanger in accordance with the present invention may be used both for heating and cooling of media, it being possible to perform both liquid-liquid treatments, liquid-vapor treatments as well as condensation of gases.

The limits of maximum pressure is entirely determined by the shell, and particularly by the flat short end surfaces thereof, whereas the sealing rings are only exposed to the differential pressure between the through-flow media.

The limits of maximum temperature is a factor principally determined by the material of the sealing rings. The expansion occuring during temperature variations in metal plates and sealing rings is entierly absorbed by the pressure spring 28 incorporated in the main embodiment of the invention comprising the tightening nut 23. In the embodiment illustrated in FIGS. 11 13 the metal plates 14 are imagined attached to the sealing rings 17 by means of welding in a projection and resistance welding unit. The entire plate assembly together with end portions 32, 33 welded thereto thus forms a rigid unit which may be built into the heat exchanger shell 1 (FIG. 11). The end portion 32 is provided with a central opening 34 to which is welded the inner end of an admission pipe 35 for one of the treatment media, and also the other end portion 33 is provided with a central opening 36 to which the outlet pipe 37 for said medium is attached through welding. The outlet pipe 37 passes through a stuffing box 38 at one 39 of the short sides of the heat exchanger such that the pipe 37 may slide in the stuff'mg box 38 upon occurrence of thermal expansions or contractions of the heat exchanger.

The heat exchanger illustrated in FIG. 14 is very similar to the one shown in FIG. 11. However, the heat exchanger in accordance with FIG. 14 presents a plate assembly which, as clearly apparent from FIGS. 16 and 17, not only is provided with outer and inner throughflow passages 40 and 41 for one of the treatment media but also has an intermediate through-flow passage 42 for the other medium. In this heat exhanger, each metal plate 14" consists of a circular disc or round 14a having a somewhat larger diameter and one circular disc or round 14b with a slightly smaller diameter. The circular discs 14a are together with their sealing rings 17a interconnected by means of a projection and resistance welding assembly and the inner discs 14b together with their sealings rings 17b are in a similar way interconnected by means of pressure welding. The radially inner edge 43 of the rounds 14a has ondulating configuration and also the radially outer edge 44 of the rounds 14b has ondulating configuration. Both edges 43 and 44 project into the annular space 42 between sealing rings 17a and 17b. In this way extensive surface expansion is obtained which favors heat transfer from one to the other of the media. To the ends of the heat exchanger is welded annular collection tubes 45, 46 having through-flow openings 47 for one of the treatment media. Collection tube 46 is through manifolds 48 connected to inlet tube 49 for one of the treatment media and collection tube 45 is via manifolds 50 connected to the outlet pipe 51 for this same medium. The outlet pipe 51 passes through a stuffing box 52 in one end portion 53 of the heat exchanger (FIG. 14).

FIG. 15 illustrates installation of a heat exchanger assembly similar to the one shown in FIGS. 14, 16, 17 in a flue gas pipe 54 of a heater 55. Collection tube 45 at the upper end of the plate assembly is via pipes 56 connected at the upper portion of the water container 56 of the heater 55 whereas collection tube 46 at the lower end of the plate assembly via pipes 57 is connected to the water container 56 immediately above the hearth 58 of the heater. Naturally, thelower collection tube 46 may be connected to the water container 56 at an even lower point.

As appears particularly from FIG. 17, the radially inner through-passage openings 41 are arranged in a central portion 59 of the inner rounds 14b. This has a favorable effect on the heat transfer between the two media. The sealing rings 17b welded to the annular discs 14b may be said to have the same effect as tube 6 in the embodiment according to FIGS. 1 and 9.

This invention provides a space-saving, simple and comparatively cheap plate heat exchanger having a high heat transfer coefficient.

The invention is not limited to the embodiments described and illustrated above but various modifications thereof are possible within the scope of the appending claims. For example, the openings in the metal plates may be displaced or offset relatively each other in many various ways. For instance, the tongues 18 may be turned in opposite directions in adjacent plates, whereby a zig-zag through-flow pattern with 180 turning directions of themedia is obtained. Furthermore, the metal plates may be formed with concentric corrugations, which considerably increases the heat transfer surface area.

What I claim is:

1. A heat exchanger comprising an elongated hollow shell, means for supplying a first fluid to one end of said shell and removing it from the other end thereof, a first tubular conduit extending axially within said shell from one end thereof and terminating adjacent the other end of said shell, a plurality of discs surrounding andspaced from said first tubular conduit and extending fi om the outer surface of said conduit to the inner surface of said shell, each of said discs having a series of inner openings adjacent said conduit and outer openings adjacent said shell, annular sealing rings in the gaps between adjacent discs, said rings lying in the space between said inner and outer openings, a second tubular conduit surrounding and spaced from said first tubular conduit and extending into said hollow shell to a point intermediate between said one end of said shell and the terminal portion of said first tubular conduit, said plurality of discs being so arranged that one end disc of the plurality sealingly engages the end of said second tubular conduit within said shell through out an annular area intermediate the inner and outer openings in said disc, a sleeve sealingly engag'ng the other end one of said plurality of discs throughout an annular area intermediate the inner and outer openings thereof, said sleeve surrounding said first tubular conduit and providing therewith a closed chamber communicating with the inner openings of the discs, an opening in said first conduit connecting the interior with said closed chamber and means for supplying a second fluid to one of said tubular conduits and removing it from the other such conduit whereby said second fluid passes and reverses from one such conduit to the other through said conduit opening and flows throughthe inner openings in said discs, the inner and outer openings of said discs being staggered to provide circuitous flow paths, an externally threaded pin closing the outerend of said first tubular conduit and extending beyond said end, a nut engaging the threads of said pin and spring means between said nut and the outer end of said sleeve for urging the sleeve against the disc members to hold said members firmly in contact with each other and with said second conduit.

2. A heat exchanger as in claim 1 wherein one end of said hollow shell is sealingly closed by a removable plate having a central opening and said second tubular conduit is sealingly mounted in said opening and wherein said first tubular conduit is sealingly mounted in said first tubular conduit and extends through it into said shell.

3. A heat exchanger as in claim 2 wherein the opening connecting the interior of said first conduit with said closed chamber comprises a longitudinally extending slot. 

1. A heat exchanger comprising an elongated hollow shell, means for supplying a first fluid to one end of said shell and removing it from the other end thereof, a first tubular conduit extending axially within said shell from one end thereof and terminating adjacent the other end of said shell, a plurality of discs surrounding and spaced from said first tubular conduit and extending from the outer surface of said conduit to the inner surface of said shell, each of said discs having a series of inner openings adjacent said conduit and outer openings adjacent said shell, annular sealing rings in the gaps between adjacent discs, said rings lying in the space between said inner and outer openings, a second tubular conduit surrounding and spaced from said first tubular conduit and extending into said hollow shell to a point intermediate between said one end of said shell and the terminal portion of said first tubular conduit, said plurality of discs being so arranged that one end disc of the plurality sealingly engages the end of said second tubular conduit within said shell through out an annular area intermediate the inner and outer openings in said disc, a sleeve sealingly engaging the other end one of said plurality of discs throughout an annular area intermediate the inner and outer openings thereof, said sleeve surrounding said first tubular conduit and providing therewith a closed chamber communicating with the inner openings of the discs, an opening in said first conduit connecting the interior with said closed chamber and means for supplying a second fluid to one of said tubular conduits and removing it from the other such conduit whereby said second fluid passes and reverses from one such conduit to the other through said conduit opening and flows through the inner openings in said discs, the inner and outer openings of said discs being staggered to provide circuitous flow paths, an externally threaded pin closing the outer end of said first tubular conduit and extending beyond said end, a nut engaging the threads of said pin and spring means between said nut and the outer end of said sleeve for urging the sleeve against the disc members to hold said members firmly in contact with each other and with said second conduit.
 2. A heat exchanger as in claim 1 wherein one end of said hollow shell is sealingly closed by a removable plate having a central opening and said second tubular conduit is sealingly mounted in said opening and wherein said first tubular conduit is sealingly mounted in said first tubular conduit and extends through it into said shell.
 3. A heat exchanger as in claim 2 wherein the opening connecting the interior of said first conduit with said closed chamber comprises a longitudinally extending slot. 